Transducers Edelmen

Question 1

Describes the property of certain materials to create a voltage when they are mechanically deformed or when pressure is applied to them

Answer 1

Piezoelectric effect

Question 2

Pzt materials change shape when a voltage is applied to them

Answer 2

Reverse piezoelectric effect

Question 3

Materials which convert sound into electricity and vise versa are called

Answer 3

Piezoelectric/ ferroelectric

Question 4

Man made transducers

Answer 4

Pzt

Question 5

Protects the internal components of the transducer from damage and insulated the patient from electrical shock

Answer 5

Case

Question 6

Prevents spurious electrical signals in the air from entering the transducer. Prevents electrical noise from contaminating the clinicals important electrical signals

Answer 6

Electrical shield

Question 7

Prevents vibrations in the case from inducing an electrical voltage in the Pzt of the transducer. Isolates or uncouples the internal components of the transducer from the case

Answer 7

Acoustic insulator

Question 8

Shaped like a coin. Characteristics of the sound beam emitted by the transducer are related to the dimensions of the active element

Answer 8

Pzt or active element

Question 9

Electrical connection between the Pzt and us system. Active element require electrical contact so during transmission the voltage can cause the crystal to vibrate and produce an ultrasonic wave

Answer 9

Wire

Question 10

Positioned in front of the Pzt at the face of the transducer. Protects the active element and increases the efficiency of sound energy transfer between the active element and the body

Answer 10

Matching layer

Question 11

Back of the active element and reduces the ringing of the Pzt. Made of epoxy resin with tungsten filaments. It enhances axial resolution

Answer 11

Backing material / damping element

Question 12

Decreasing order of impendance

Answer 12

PZT > matching layer > gel > skin

Question 13

Thickness of the matching layer

Answer 13

1/4 wavelength thick

Question 14

Thickness of active element

Answer 14

1/2 wavelength thick

Question 15

3 consequences of backing material

Answer 15

decreased sensitivity, wide bandwidth, low quality factor

Question 16

Less able to convert low level sound reflections into meaningful electrical signals

Answer 16

Decreased sensitivity

Question 17

Range of frequencies in a pulse. Difference between the highest and lowest frequencies

Answer 17

Bandwidth

Question 18

Long duration events have what type of bandwidth

Answer 18

narrow

Question 19

unitless number that is inversely related to bandwidth. main frequency divided by the bandwidth

Answer 19

Quality factor

Question 20

A short, dampened pulse has a ___ Q factor

Answer 20

lower

Question 21

Q factor and bandwidth are ____ related

Answer 21

inversely

Question 22

Destruction of all microorganisms by exposure to extreme heat, chemical agents, or radiation

Answer 22

Sterilization

Question 23

Application of a chemical agent to reduce or eliminate infectious organisms on an object.

Answer 23

Disinfection

Question 24

Transducers should be disinfected with

Answer 24

Cidex or other cold germicides

Question 25

Backing material ___ duty factor and _____ quality factor

Answer 25

decreases

Question 26

Characteristics of high frequency PW imaging transducers

Answer 26

Thinner Pzt crystals & Pzt with higher speeds

Question 27

Characteristics of low frequency PW transducers imaging transducers

Answer 27

Thicker PZT crystals and lower speeds

Question 28

Terms describe the shape and regions of a sound beam

Answer 28

Focus Near zone Focal length / near zone length Far zone Focal zone

Question 29

Location where the beam is the narrowest

Answer 29

Focus / focal point

Question 30

Region from the transducer to the focus

Answer 30

Near field / fresnel zone

Question 31

Distance from the transducer to the focus

Answer 31

Focal length / focal depth / near zone length

Question 32

Region that starts at the focus and extends deeper

Answer 32

Far zone / far field / Fraunhofer zone

Question 33

Region around the focus where the beam relatively narrow

Answer 33

Focal zone

Question 34

At the transducer the beam diameter equals

Answer 34

Transducer diameter

Question 35

At the focus the beam diameter is

Answer 35

1/2 transducer diameter

Question 36

A 2 near zone lengths, the beam diameter

Answer 36

Equals transducer diameter

Question 37

Deeper than 2 near zone lengths the beam diameter is

Answer 37

Wider than transducer diameter

Question 38

What characteristics of a fixed focus transducer determine the focal depth

Answer 38

Tranducer diameter and frequency of sound

Question 39

A smaller diameter Pzt and low frequency creates a ____ focus

Answer 39

Shallow

Question 40

What transducers is steered by a motor or reflecting mirror

Answer 40

Mechanical and annular phased array transducer

Question 41

4 transducers that focus the us beam electronically

Answer 41

Linear switched array, linear phased array, annular phased array, and convex/curvilinear array

Question 42

The minimum number of active elements in a mechanical transducer is

Answer 42

1

Question 43

Describe a linear phased array transducer

Answer 43

rectangular, 1/2 to 1/4 wavelength wide

Question 44

How are the pzt crystals of a linear phased array fired

Answer 44

At almost exactly the same time

Question 45

Describe a linear sequential array transducer

Answer 45

rectangular, 1 wavelength wide

Question 46

What component of an ultrasound system is made of lead zirconate titanate

Answer 46

Transducers active element

Question 47

How thick is an active element of a 3 mhz pw transdcuer

Answer 47

Half the wavelength of the sound wave in the pzt

Question 48

What component of the transducer is made from a slab of epoxy embedded with tungsten particles

Answer 48

Damping material

Question 49

Impedance from highest to lowest

Answer 49

PZT, matching layer, gel, skin

Question 50

Impedance from lowest to highest

Answer 50

skin, gel, matching layer, pzt

Question 51

How thick is the matching layer of a 2 mhz pw transducer

Answer 51

one quarter the wavelength of sound in the matching layer

Question 52

The spatial pulse length ___ with backing material

Answer 52

decreases

Question 53

To calculate bandwidth

Answer 53

highest frequency - lowest frequency

Question 54

Damping material ____ sensitivity

Answer 54

decreases

Question 55

What helps determine the frequency of the sound produced by the transducer of a cw us system

Answer 55

US system electronics. It has nothing to do with the crystals thickness and speed

Question 56

2 characteristics to determine the frequency of sound in a pulse

Answer 56

Thickness and speed of the active element

Question 57

Characteristics of a high emitted acoustic wave frequency

Answer 57

Thin element and high prop speed

Question 58

the higher the frequency the length of the near zone will be

Answer 58

longer

Question 59

____ diameter and ____ frequency will have a deep focus (long near zone)

Answer 59

large diameter and high frequency

Question 60

3 terms to describe a shape of a sound created by a tiny fragment of pzt

Answer 60

Spherical, huygens wavelet, and V shaped